Evaluation of the Malvern Spraytec with inhalation cell for the measurement of particle size distribution from metered dose inhalers.

The purpose of this study was to evaluate the Malvern Spraytec with inhalation cell attachment as a means of analyzing the particle size distribution of aerosols from pressurized metered dose inhalers (pMDIs). The aerosol particle size distribution of various commercially available, placebo, and experimental pMDI formulations was determined using Spraytec under various experimental conditions and the relevant data were compared with the Andersen cascade impactor data. The Spraytec volume median diameter (Dv 50) values for commercial chlorofluorocarbon- and hydrofluoroalkane (HFA)-based pMDIs were respectively smaller and higher compared with their reported mass median aerodynamic diameter values. It was possible to obtain a close agreement between Spraytec Dv 50 and the reported mass median aerodynamic diameter values for a solution-type pMDI formulation, Qvar 50, by equilibrating the pMDI to 55 degrees C before the measurement and using a 20-cm throat extension. Incorporation of a nonvolatile solvent propylene glycol (PG) in placebo pMDIs (15% w/w ethanol, 0.5-20.0% w/w PG in HFA 134a) showed an increase in Dv 50 with increasing concentration of PG. Furthermore, it was possible to obtain a correlation (R(2) = 0.8037) between Spraytec and Andersen cascade impactor data for the experimental nimesulide-pMDI formulations containing 0.1% w/w drug, 0.25-10% w/w PG, and 15% ethanol in HFA 134a.

Effects of monensin liposomes on the cytotoxicity, apoptosis and expression of multidrug resistance genes in doxorubicin-resistant human breast tumour (MCF-7/dox) cell-line.

We have evaluated the effects of monensin liposomes on drug resistance reversal, induction of apoptosis and expression of multidrug resistance (MDR) genes in a doxorubicin-resistant human breast tumour (MCF-7/dox) cell line. Monensin liposomes were prepared by the pH-gradient method. MCF-7/dox cells were treated with various anticancer drugs (doxorubicin, paclitaxel and etoposide) alone and in combination with monensin liposomes. The cytotoxicity was assessed using the crystal violet dye uptake method. The induction of apoptosis in MCF-7/dox cells was assessed by established techniques such as TUNEL (terminal deoxynucleotidyl transferase-mediated nick end labelling) staining and caspase-3 assay. The effect of monensin liposomes on doxorubicin accumulation in MCF-7/dox cells was monitored by fluorescent microscopy. Finally, the expression of MDR genes (MDR1 and MRP1) in MCF-7/dox cells following the exposure to doxorubicin alone and in combination with monensin liposomes was evaluated by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Our results indicated that monensin liposomes overcame drug resistance in MCF-7/dox cells to doxorubicin, etoposide and paclitaxel by 16.5-, 5.6- and 2.8-times, respectively. The combination of doxorubicin (2.5 microg mL(-1)) with monensin liposomes (20 x 10(-8)M) induced apoptosis in approximately 40% cells, whereas doxorubicin (2.5 microg mL(-1)) or monensin liposomes (20 x 10(-8)M) alone produced minimal apoptosis (<10%) in MCF-7/dox cells. Fluorescent microscopy revealed that monensin liposomes increased the accumulation of doxorubicin in MCF-7/dox cells. RT-PCR studies demonstrated that the expression of MDR1 and MRP1 was increased by 33 and 57%, respectively, in MCF-7/dox cells following treatment with doxorubicin (2.5 microg mL(-1)) for 72 h as compared with control MCF-7/dox cells. Furthermore, the levels of MDR1 and MRP1 in MCF-7/dox cells exposed to both doxorubicin and monensin liposomes showed a modest decrease as compared with MCF-7/dox cells treated with doxorubicin alone. In conclusion, the delivery of monensin via liposomes provided an opportunity to overcome drug resistance.

Effect of monensin liposomes on the cytotoxicity of anti-My9-bR immunotoxin.

The purpose of the study was to evaluate the utility of monensin liposomes in the enhancement of in-vitro cytotoxicity, apoptosis and in-vivo antitumour activity of anti-My9-bR immunotoxin. Monensin liposomes were prepared and studied for the enhancement of in-vitro cytotoxicity and apoptotic response of anti-My9-bR immunotoxin against both sensitive and resistant human promyelocytic leukemia HL-60 cells by MTS/PES method and acridine orange staining, respectively. Further, the in-vivo cytotoxicity enhancement of anti-My9-bR immunotoxin by monensin liposomes was studied in a survival model of severe combined immunodeficient (SCID) mice bearing intraperitoneal HL-60 tumours. The in-vitro cytotoxicity of anti-My9-bR immunotoxin was enhanced 580 fold and 4.7 fold against sensitive and resistant HL-60 cells, respectively, by monensin liposomes (5 x 10(-8) M). The combination of anti-My9-bR immunotoxin (50ng mL(-1)) with monensin liposomes (5 x 10(-8) M) produced apoptosis in 40% of cells, whereas the apoptotic response was minimal (< 10%) in anti-My9-bR immunotoxin- or monensin liposome (alone)-treated HL-60 (resistant) cells. In SCID mice bearing HL-60 tumours, anti-My9-bR immunotoxin (75 microg kg(-1) administered intravenously every other day for a total of five courses) showed a median survival time of 20 days, which was no different than that of vehicle control- or monensin liposome-treated mice. However, anti-My9-bR immunotoxin (75 microg kg(-1)) in combination with monensin liposomes (4 microg kg(-1) monensin), administered every other day for a total of five courses, was found to prolong the survival of 20% of mice for more than 46 days. Our results indicate that, despite anti-My9-bR immunotoxin being ineffective in the HL-60 tumour model, its combination with monensin liposomes could improve the antitumour response.